The length and lifetime of the plasma channel induced by nanosecond laser in air is investigated. The energy of Nd:YAG laser (pulse energy about 2.1 J) was averaged to a straight line through beam shaping and a 1 m long plasma channel was formed by laser breakdown. The lifetime of this channel was detected with intensified charge coupled device (ICCD) and the electric continuity was studied by electrical detecting method. The experimental results indicate that the continual electric conduction spatial length of nanosecond laser-induced air plasma channel can reach near 80 cm, with the survival life above 500 ns. The channel total resistance is mainly constituted of the coupling resistance. These results are helpful for researching the femtosecond laser induced plasma channel, and also provide experimental evidences for prolonging the decay time and length of laser-induced air plasma channel in technical applications.